Technical Abstract:
When biochar is added to degraded soil, it can improve fertility, increase crop production, and act as a long-term sink for atmospheric carbon (C). Biochars along with bio-oils and gasses are produced when biomass is pyrolyzed. Biochar pyrolysis at high temperatures (500 to 700°C) maximizes bio-oil and gas production. These harsh conditions cause biochar to be recalcitrant to degradation since C structures are condensed into polymeric aromatic structures. The recalcitrant nature may be desirable if the goal is to increase C sequestration for millennia. However, if the goal is soil improvement, then pyrolysis conditions can be altered to produce biochars with less aromatic character and more surface functional groups. We propose that the pyrolysis process can be customized to produce designed biochars that are either recalcitrant or have properties that remediate selective characteristics of degraded soils. Preliminary results showed that switchgrass biochar pyrolyzed at a lower temperature (250°C) retained more O-functional groups and had higher total acidity than higher temperature biochar (500°C). Biochars produced from four feedstock’s are being examined in laboratory incubation experiments to examine the influence of high and low pyrolysis temperatures on soil physical and chemical characteristics. [GRACEnet Publication]